This chapter focuses on attitudes towards marriage and unmarried cohabitation of Czechs and their actual family behavior. Firstly, it answers the question if unmarried cohabitations are becoming more popular and who prefer it. Can we explain an increase of non-marital fertility by the spread of unmarried cohabitations? Secondly, does a character of unmarried cohabitation differ from a marriage and are there any differences between marital and non-marital families with children?